DE2363655A1 - RUBBER MIXTURE - Google Patents

Description

The invention relates to a rubber compound to be used on steel clad with zinc or a zinc alloy adheres and maintains this improved adhesion even after aging in the heat.

Many different methods have been proposed to with their help, an adhesion of highly unsaturated rubber, such as natural rubber, butadiene rubber or styrene-butadiene copolymer rubber on steel cord should be effected or improved; a procedure should be mentioned in particular, in which an organic cobalt salt is added to the rubber mixture (described in JA-PS 29 739/69). In particular it is known that rubber compounds which have been prepared by mixing natural rubber and / or or synthetic rubber with cobalt naphthenate is excellent Have adhesiveness to steel cord. All-

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However, it has been shown that such mixtures have the disadvantage that their adhesion with advancing aging gradually subsides under the influence of heat and that it becomes difficult is to maintain this property over a longer period of time,

Furthermore, it is generally known to mix rubber with magnesium oxide, the magnesium oxide not only as Vulcanizing agent for types of rubber containing halogens, but also as an inorganic accelerator or additive when processing natural rubber and synthetic rubber.

Magnesium oxide is also often incorporated into a rubber compound, which has substances other than cobalt carboxylate as an additive and has excellent adhesiveness to it Owns metal. In this pail, the amount of magnesium oxide is more than 5% by weight, for example from J.A-PS 11 252/71 is seen. If the amount of magnesium oxide is below 5% by weight, As has been shown, the rubber mixture has only a very low level of adhesion to steel cord.

The invention is based on the object of providing a rubber mixture with particularly high adhesion to zinc or Provide zinc alloy clad steel that is particularly resistant to aging in heat.

The invention therefore provides a rubber mixture with a content of cobalt carboxyl at, which is linked to zinc or a zinc alloy clad steel and is characterized by having 0.1 to 4.0 parts by weight of magnesium oxide Contains 100 parts by weight of rubber each.

The rubber to be used for the mixture can be natural rubber, Polyisoprene rubber, polybutadiene rubber, styrene

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Butadiene copolymer rubber (SBR), ethylene propylene diene terpolymer Kau.tsch.uk (EPDM) or a mixture of several of the types mentioned. The mixture preferably contains natural rubber.

The term "steel" here includes steel cord, steel plates and the like are summarized, however, for the sake of simplicity, the invention is explained in terms of steel cord.

The steel cord to be used in the present invention is zinc or a zinc alloy, in particular with brass, plated. Plating with zinc is preferably carried out by electroplating Paths with high current density and short treatment time.

For the brass-plated steel cord in question here copper and zinc become part of the brass plating usually used in a weight ratio of Cu / Zn = 55:45 - 80:20, preferably 70:30.

According to the invention, the rubber is mixed with cobalt carboxylate, to make it adherent to the steel cord, and also magnesium oxide is added to it to facilitate adhesion between Rubber and corduroy too, to maintain after aging. For this purpose, the amount of magnesium oxide, which must be added, 0.1 to 4.0 parts by weight per 100 parts by weight Rubber.

Should the rubber mixture on zinc-plated steel cord adhere, the proportion of magnesium oxide is preferably 0.1 to 2.0, in particular 0.3 to 1.0 parts per 100 parts by weight Rubber. If the rubber mixture is to adhere to brass-plated steel cord, the proportion of magnesium oxide is preferably 0.5 to 4.0 and in particular 1.0 to 3 »0 parts by weight per 100 parts by weight of rubber.

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If the proportion of magnesium oxide exceeds 4.0% by weight, the mass adheres to the steel cord much worse before aging _/ and if the magnesium oxide proportion is less than 0.1% by weight, the effect is practically the same as Hull «

As cobalt carboxylates which are added to the mixture, the cobalt salts of cycloaliphatic acids, such as cobalt naphthenate, the cobalt salts of unsaturated fatty acids such as cobalt oleate, the cobalt salts of saturated fatty acids such as cobalt stearate and the like can be used, among which the cobalt naphthenate is particularly preferred » the amount of einzuarbeitendem Kobaltcarboxjlat 'is not limited, however, preferably used i to 5 parts by weight per 100 parts by weight rubber "is namely the amount of cobalt as cobalt carboxylate below 1 ew _o -%, it can be the intended Do not achieve the effect and if the additive content exceeds 5% by weight, the quality of the rubber is adversely affected.

The usual additives can be incorporated into the rubber mixture according to the invention during its production, such as vulcanizing agents, vulcanizing activators ^: "accelerators," fillers, plasticizers, antioxidants and other substances which

"Facilitate processing" ■

Compared to zinc or zinc alloys, tdle brass and the like, hatred according to the invention, as already mentioned, has a particularly strong ability to adhere; _v € he aueii after ILTERN in AEET heat is maintained _o MSSE property makes them suitable besonders- zut ¥ erwen & i2ng for _Ssifea? steel-reinforced

The drawing is a graphic representation from which the half of the content of the mass aa magnesium oxide and the BIM ~ ¥ © rt for the permanent adhesion (BII retention)

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The examples, in which the parts mean parts by weight, serve to explain the invention in more detail.

example 1

A rubber mixture of 70 parts of natural rubber, 10 Parts of polybutadiene rubber and 20 parts of styrene-butadiene copolymer rubber (SBR) was mixed with various additives and magnesium oxide (MgO); the different approaches are listed in Table 1. The mixture was then mixed with a zinc-plated steel cord 3.2 mm in diameter Vulcanized for 30 min at 148 ° C in a peeling mold .

The same additives, but without magnesium oxide, were chosen for a comparison sample.

A peeling test at a peeling speed was carried out on the rubber mixture test pieces with a steel cord insert obtained in this way of 50 mm / min to measure the adhesive strength of the rubber on the steel cord. In this measurement sfird is the value for the force that is necessary to vulcanize the Rubber mass with a peeling speed of 50 mm / min peel off the steel cord to a length of 5 cm, divided by five and the value thus obtained then represents the "steel peel force" before aging.

To determine the Stahlabschälkraft after aging, the specimens were aged for 150 minutes at 140 ⁰ C and then subjected to the same peel test.

The decline in adhesion with aging is usually expressed in terms of "permanent adhesion" or retention in%, a value that can also be expressed as DIN retention

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can. The permanent adhesion is determined using the following equation:

permanent adhesion _ steel peel force after aging. in% ~ steel peeling force before aging

The DIN retention is the permanent adhesion for steel cord according to German standards, the standard value for the DIN retention 60 kg / cm for steel of 3.2 mm diameter. The term "DIN-Retentidn" therefore corresponds to the following equation;

DIN retention steel peeling force after aging _ % " ^β: 60 kg / cm" The results are shown in Table 1.

Tabel

409829/06 99

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ta «**., *«, No. 1 2 3 4th 5 6th
Comparison attempt 70 70 70 70 70 70 Polybuteaienkautseh.uk 10 10 10 10 10 10 SBB 20th 20th 20th 20th 20, 20th ZnQ ■ ~ ■ 5 5 5 5 5 5 Accelerate 0.75 0.75 0.75 0.75 0.75 0.75 antioxidant 2 2 2 2 2 2 ProcessingÖX 5 5 5 5 5 5 ΗΔΕ-Huss 3 50 50 50 50 50 50 sulfur 5 5 5 .5 5 5 Eötoaltnaphthlieiiat 3 3 3 3 3 3 HgO 0.1 0.5 1.0 2.0 Steel peel force 101 101 95 85 81 101 aging Steel absorption after . 65 77 79 72 62 47 aging. bXeibea.de adhesion 64 76 83 85 77 47 Dll-Eeteatioa 108 128 132 115 108 78

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loeceler MSA (protected trade name, manufacturer Ouchi Shinko Kagaku Kogyo KK j H ~ 03cyaethylene »2 ~ be: n.2olsul £ enamid) Nocrac D (protected trade name, manufacturer Ouchi Shxnko Kagaku Kogyo KE ₆ ; phenyl ~ ß ~ naphthylamine) highly abrasion-resistant furnace soot

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As can be seen from Table 1, the peeling force changes prior to aging by the addition of magnesia to the mixture, however, the peeling force after aging is not essential much higher than without the addition of magnesium oxide.

In the drawing, the amount of magnesium oxide is plotted on the abscissa and the DIÜF retention on the ordinate. As can be seen, the amount _% of magnesium oxide is preferably within a range from 0.1 to 2.0 parts by weight per 100 parts by weight of rubber and the DIN retention is then more than 85 % of the standard value.

Example 2

Various rubber compounds were prepared, which are identified in Table 2 with the numbers 7 to 14. Cobalt naphthenate was used as the cobalt carboxylate and the amount of magnesium oxide was varied as indicated. An adhesion test was carried out on the mixtures, in which the sample was prepared in such a way that a number of types of steel cords clad with brass (Cu / Zn = 70% 30) were used , which each had a diameter of 3 ₅ 2 mm, pressed onto a sheet of the corresponding rubber mixture and vulcanized the piece for 30 min at 148 ⁰ G e _a -

The adhesion test was carried out by pulling off the steel cord τοπ

the rubber baian performed.and-the adhesion mr & e la, kg / cord geiessea «

The samples were aged for 150 min at 140 ⁰ O TIAD then the adhesion test described above iisiterworfea

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The adhesion test on test pieces is used for comparison carried out in which the rubber mixture does not contain eobalt naphthenate and / or contained magnesium oxide.

Tabel

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TABEL

Fs uchukmischsang $ fr _e 7th 8th 9 100 100 10. 11 12 ' 13th 14th O Haturkaut s chuk Comparison.versu.ehe 5 5 100 100 100 100 100 I. Zinc white 100 0.75 0.75 5 5 5 '5 5. Ihiazole accelerator 5 2. 2 0.75 0.75 0.75 0.75 0.75 Phenyl-ß-naphthylamine 0.75 5 5 2, 2 2 2 2 Processing Ö 1 2 50 50 ■ 5 5 5 5 5 HiJ = RuB 5 4th 50 50 50 50 50 Jknsa * fcg sulfur 50 - 2 4th 4th • 4 4th Cob al tnaphthenate 4- o, 5 2 2 2 2 2 Magnesium oxide «. 4? 100 0.5 1 2 3 4th Adhesion in front of the Al
tern (Indes) * - 4-7 51 102 100 98 98 94- read- Adhesion according to the Al
tern (index) * 45. 60 78 97 88 62 result-
would do 42

': The adhesion index before aging in the Eautsehukmisohung was No. 9

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From Table 2 it can be seen that the fiction, contemporary Rubber compounds (ITr. 10 - 14) after aging with regard to, the adhesion to the usual rubber compounds (No. 7-9) are clearly superior and that the adhesion before aging substantially corresponds to that of conventional rubber compound no. 9.

Example 3

Various rubber mixtures were prepared, the cobalt carboxylate being cobalt stearate, cobalt oleate or cobalt naphthenate were used and the approach in the manner indicated in Table 3 was changed. The mixes were dem in Example 2 described adhesion test subjected.

For comparison, rubber compounds that did not contain magnesium oxide were also selected here.

As can be seen from Table 3, the invention Rubber compounds have a significantly higher adhesion before and after aging than the equalizing compounds.

Tabel

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SABEL '

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ι 1 * 1 ι 'Ίι ι ■ -' ¹ V '"! ^ l · ύ ■! ι i * ■ ι'. ' f. ' f Ansats ! "attu 'rubber 9 I. 15th 100 5 16 17th 18th 19th 2 ? 0 _OT t _S eM »isetan _S Hr. SBE Ir = 150 Comparative " 0.75 CHEAP / equal 5 Zinc white attempt 2 100 try 80 / request 50 80 Thiasol accelerator 100 5 80- 20th 80 4th 20th Phenyl- β-naphthylamine 50 5 20th 5 20th - 5 Processing oil 5 '4 0.75 5 5- - 0.75 HAP-ßuss 0.75 2 0.75 0.75 0.75 2 2 sulfur 2 2 5. 2 2 5 Kola old naphthenate 5 50 5 5 75 50 i β S u = " Cobalt stearate 50 .4 50 50 4th would do Complete oleat 4th 85 _ 4th 4th 36 - Magpies III 2 2 2 2 - Adhesion in front of the - 43 =, - 2 tem (Inaex) '2 - - 2 Adhesion aacii to the Al 87 2 78 tern (index) 100 76 80 • 81 70 51 38 71

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Claims (4)

Claims 1. Rubber mixture with good adhesion to steel plated with zinc or a zinc alloy, which contains a cobalt carboxylate as an additive, characterized by an additional content of 0.1 to 4 parts by weight of magnesium oxide wxt 100 parts by weight of rubber. 2. Rubber mixture according to claim 1, characterized in that the cobalt carboxylate is cobalt naphthenate, Cobalt oleate or cobalt stearate is present. 3. Rubber mixture according to claim 1 or 2, characterized in that natural rubber is used as the rubber component, Polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer rubber, Xethylene-propylene-diene terpolymer rubber or a mixture of several of these types of rubber is available, 4. Rubber mixture according to one of the preceding claims with particular adhesion to zinc-plated steel, marked by the fact that the magnesium oxide in an amount of 0.1 to 2.0 parts by weight ge 100 parts by weight Rubber is present. 5 ° rubber mixture according to one of claims 1 to 3 * special adhesive strength to steel plated with zinc alloys, characterized in that the magnesium oxide in an amount of 1.0 to 3 »0 parts by weight ^ e 100 parts by weight of rubber is present. 86XXV 409829/0699 Lee.rseite